Stream Channel Responses to Streamflow Diversion on Small Streams of the SnakeRiver Drainage, Idaho

摘要

The effects of channels of small, low-head seasonal water diversions in the SnakeRiver drainage were investigated. Channels below small diversions were compared to the channels immediately above the same diversions to determine if differences in flow conveyance, substrate sediment size distribution, or streamside vegetation density were present. Estimates of flow conveyance were greater above the diversions, as measured by the area between the edge of vegetation on both banks, and by frequent-flow indicators, which generally approximated bankfull state. No significant difference in substrate particle size or in channel roughness was found between channels above and below diversions. Although use histories of the diversions were not available, limited observations and conversations with users suggest that many of the diversion structures did not substantially divert high springtime flows so that passage of channel-forming flow probably occurred.